It has been proposed to form openings in metal bodies, including tubular metal bodies, by used of thermal drilling techniques, also known as flow drilling techniques. See, for example, U.S. Pat. Nos. 3,939,683, 4,132,097, 4,185,486, 4,428,214 and 4,454,741. In general, a rapidly rotating piercing tool of hard material is brought into contact with an external surface of the wall of the body. Frictional heat and pressure of the piercing tool against the body cause material to flow axially and radially forming an opening through the wall of the body. The opening is surrounded by an annular collar formed by thermal flow of material along from the tool. That is, the material that is removed to form the opening flows along the surface of the tool to form the annular collar, as distinguished from forming chips or shavings as in typical drilling operations. A general object of the present invention is to utilize thermal drilling techniques of this type to secure two metal components to each other. An illustrative, but non-limiting, exemplary embodiment of the invention employs thermal drilling techniques to join a component holder to the external surface of a tubular fuel rail for an internal combustion engine.
A method of securing a metal component to a body having a metal wall, in accordance with a first aspect of the present invention, includes placing the component against the body such that a wall of the component is in external surface contact with the wall of the body. An opening is then thermally drilled through the abutting walls of the component and the body, causing thermal flow of material on opposite sides of the abutting walls that, when hardened, joins the component to the body.
A method of securing a metal cup-shaped component holder to an external surface of a hollow tubular fuel rail for an internal combustion engine, in accordance with an exemplary embodiment of the invention, includes locating the component holder such that a base wall of the holder is in external tangential surface contact with the fuel rail, and forming an opening through the base wall and through the fuel rail where the base wall is in contact with the fuel rail, by a thermal drilling process, to secure the holder to the fuel rail by thermal flow of material into the holder and the fuel rail surrounding the opening. A fuel rail assembly in accordance with another aspect of the invention includes a hollow tubular metal fuel rail having an external surface and at least one metal component holder externally attached to the fuel rail. The component holder has a flat wall with a first portion in external tangential contact with a second portion of the external surface. The component holder is attached to the fuel rail by means of an annular collar formed by flow of metal from the wall and the tube around an opening that extends through the first and second portions.